The invention relates to an electromagnetic actuator having a single armature plunger that reciprocally shuttles between magnetic paths. A pair of coils are energizable to create magnetic fluxes having portions of their linkage paths in common, including through the plunger.
When either coil is energized, a flux path is created around that coil through the plunger, and another flux path is created around both coils through the plunger. The ratio of the permeances of the two paths is controlled such that one path always overpowers the other, to insure plunger movement in either direction.
In one aspect of the invention, movement of the plunger from one position to the other induces a voltage signal in the nonenergized coil. This voltage signal may be used as an indication of plunger movement, whereby to afford feedback verification of actuation of the plunger to its other position. This feedback verification is afforded without additional sensing circuitry; instead, existing flux linkages are used.
In further aspects of the invention, the electromagnetic actuator is inexpensive, compact, and extremely fast.